Upwash and sidewash induced by certain control surfaces in a supersonic flow

Abstract

Dr. Lagerstrom's development of the conical flow theory to apply to upwash and sidewash problems (see reference 1) has been applied to the case of a deflected roll control surface. The upwash behind, and in the plane of, the deflected control surface at 0, 1, 4, and 9 chord lengths behind the wing is calculated. The whole upwash-sidewaeh field, an infinite distance downstream of the control surface, (in the Trefftz plane), is also calculated. It is shown that a rolling moment is induced on any aerodynamic surface - vertical, horizontal, or oblique - that lies in the wake of the deflected control surface. This induced rolling moment is in the reverse direction of that prescribed by the deflection of the roll control surface. One simple case is cited where the magnitude of the induced rolling moment is larger than that produced directly by the roll control surface, thus causing a reversal of the roll direction. An induced yawing moment may also be encountered if a vertical aerodynamic surface, not symmetrical with respect to the plane of the wing, is present in the wake of the deflected control surface.